This research program is designed to examine the chemical and biologic properties of slime (the refined polysaccharide-containing component isolated from the extracellular slime layer) produced by Pseudomonas aeruginosa, and the possible role of slime in experimental infection of mice. Through the use of radioisotopes the distribtion and possible predilection of slime for certain target organs or tissues will be determined. Mechanisms by which leucopenia, and subsequent lethality, are produced will include examination of bone marrow cells. The coating or association of slime with leucocytes will be studied by serological techniques, and through the use of radioisotopes. Enzymic and chemically produced fragments, derived from the purified slime molecule, will delineate the determinants responsible for leucopenia, lethality, antiphagocytosis, interaction with specific antibodies and ability to stimulate the production of protective antibodies. Fragmentation studies, using slime molecules obtained from different strains of P. aeruginosa will provide the basis for the expression of similar biologic properties, despite the presence of distinctive protectve antigens. The influence of bacteriophage lysogenization on the chemical and biologic characteristics of slime, and its effect on experimental infection will be determined. Mouse macrophages and polymorphonuclear leucocytes will be compared for bacteriocidal activity against P. aeruginosa, and antibody requirements for the bactericidal activity of these two cell populations will be determined.